M innesota Governor Tim Walz worries that the violence in his state could produce a national rupture. “I mean, is this a Fort Sumter?” he mused today in an interview in his office at the state capitol. The island fortification near Charleston, South Carolina, is where Confederate forces fired the first shots of the Civil War in 1861. Now it’s federal forces that are risking a breach. “It’s a physical assault,” Walz told me. “It’s an armed force that’s assaulting, that’s killing my constituents,